The duplication process of Escherichia coli will be investigated, with emphasis on the mechanisms which control the frequency of chromosome replication and cell division. The following projects will be undertaken to investigate the molecular mechanisms involved in initiation of chromosome replication: 1) Analysis of the effects of oriC-containing plasmids on host cell growth, 2) Determination of the timing of oriC plasmid replication during the division cycle of E. coli B/r, 3) Studies on the requirements for RNA and protein synthesis in oriC plasmid replication, 4) Examination of cloned chromosomal fragments which suppress temperature-sensitive dnaA mutants, 5) Analysis of the interaction between the dnaA gene product and RNA polymerase during initiation of chromosome replication, and 6) The kinetics of synthesis of DNA-binding proteins with respect to initiation and elongation of the E. coli chromosome.